1. Field of the Invention
This invention relates to cutting tools and more particularly to adjustable position utility knives.
2. Description of Related Art
U.S. Pat. No. 4,443,942 of Demeter for a "Tool for Trimming Lapping Edge Portions of Sheet Material" shows a base 22 with a central guide slot 44 through which a cutting blade 26 is extended. Blade 26 is held in a handle 24 which pivots about pin 50 supported by post 48 on base 22. Blade 26 is a commercial blade apparently identical to the blades of conventional utility knives. There is an adjustment device 46 which controls how deeply the handle can be pushed down by the operator to drive the blade 26 through the slot 44 to cut the work below the slot. As contrasted with your invention, in Demeter the blade handle 24 is pivoted relative to the base 22 rather than being in a fixed position relative to the base and although the depth of cut is controlled, it is done differently from the device 46 since the blade handle 24 is pivoted. This is the only reference which is adapted for a similar use to the tool of the present invention in that it provides excellent lateral angular stability of the blade relative to the work and it is useful to cut sheet rock, etc. A significant difference is that the base 22 is supported not by the work but by the wheels 36 which ride on the work being trimmed by the blade 26. As the work sheets 14 are overlapped at edge portions 20, the wheels are required to hold the tool above the sheets 14.
U.S. Pat. No. 5,203,086 Dann "Cutting Apparatus" shows a hand held cutter with a blade 22 seen in FIG. 9 which can be slid down by pushing down on the blade holder when knurled nut 31 is loosened for adjustment. Note that it is stated at Col. 3, lines 41-46, the blade 22 is "mounted outboard of the body 10, so that the region of cutting contact 60 of the blade is readily visible to the user so that he can see exactly where the cut is being made, and where the desired path of the cut lies." There is a flat surface 16 on the bottom of the body of the tool which provides a narrow guide surface along which the blade is drawn to stabilize it in its position at right angles to the surface of the work being cut. (Col. 2, lines 60-65. The guide surface of this invention is a wide base which provides stability of the blade. The "base" 16 of Dann is very narrow and provides a poor degree of angular stability. Another difference is that in your invention the blade contact with the work is obscured by the blade holder body and the direction can be seen at the front and back ends of the blade holder. In addition, the blade of Dann appears to slide at a fixed angle into and out of the retracted position whereas in the present invention, in its current design, the adjustment of the blade involves a quick adjustment step, when the tool is not being used to cut, involving rotation of the blade through an angle to change the depth of the cut made by the blade.
U.S. Pat. No. 4,148,142 Sullivan et al. "Carpet Cutter" shows a blade holder assembly 40 shown in FIG. 4A with opposed leg portions 14, 14' through which a carpet C is pushed in FIG. 2. A handle 20 pivots about journal element 28 to push a blade holder 40 carrying a blade 36 which can extend down through an opening (hole) 18 in the upper leg portion 14 into an opening (hole) 18' in the lower leg portion 14'. The blade 36 is retained in an adjustable position in the blade cover 42 by a bolt 62 which fastens the blade into hole 64 in handle 24, as seen in FIG. 6. The locking set screw 34 is used to set the handle 20 with the cutter blade 36 from left to right in the wide holes 18/18'. There is no such feature in your invention. A significant difference from your invention is that the blade is not rigidly held at any fixed depth below a bottom surface of a broad flat surface upon which the cutting tool rides. In addition, the provision of the extra leg 14' above which the carpet C is supported is an element which would interfere with the use of a tool designed in accordance with your invention. A basic difference is that the base does not rest upon the work, but the blade is slipped between the legs of the base in Sullivan et al.
4. U.S. Pat. No. 5,438,757 Weschenfelder "Multifunction Cutting Tool" shows a blade 40 which can be rotated, which is retrieved from storage slot 39 by loosening screws 16a and 16c. A screw driver is inserted into slot 43 in blade 40. Blade 40 is rotated around screw 16a to an extended position. See Col. 3, lines 1-7 and Col. 4, lines 4-18. There is also a fixed blade 80 and a foot 76 in blade holder 10. PA1 5. U.S. Pat. No. 4,761,884 Nguyen et al. "Device for Trimming to a Net Shape the Edge of a Metal Skin" seems to teach a variation on a rotary saw with a rotary blade 28 seen in FIG. 3 turned by a saw (motor) 12. Nguyen et al. calls for a power driven rotary saw and a guide means for contacting the edge of a second skin.
U.S. Pat. No. 4,713,885 Kaliak et al "Safe Utility Knife" describes a conventional trapezoidal utility knife blade 19 with two top notches 20 fits into a slidable carrier 15 which includes an internal lug 16 which holds the blade in position between the shell halves 10 and 11 of the handle. The lever 23 is used to slide the blade in and out of the handle. It is shown in the blade retracted position in FIG. 2 and the blade extended position in FIG. 3.
U.S. Pat. No. 5,425,175 Rogers "Knife with Multiple Cutting Positions" shows how latching of a pivotable multiple position blade can be achieved. In FIGS. 1 to 4 of Rogers a biased engagement means 8 engages positioning means 6 and fixes blade 2 in each of two angular cutting positions (first cutting position 18 (FIG. 1) and a second cutting position 19 (FIG. 2)). The tail 12 of the blade 2 is locked in position by a locking member 15 which is biased by a coil spring 22 against the tail 12. The locking member 15 can be released from engagement with the tail 12 by an actuator 21 sliding through slot 34 seen in FIGS. 3 & 4. In the embodiment of FIGS. 5 and 6 blade 2 has three slots 40 (first cutting position 41), slot 42 (second cutting position 43) and 44 (folded or closed position 45) into which engagement tab 39 is urged by spring 11.
U.S. Pat. No. 4,868,985 Rehm "Utility Knife" describes a slide 12 located in a knife handle housing 10 with a pin 14 on which the blade 16 is placed for sliding in and out of the housing 10. The slide 12 is held in retracted position by a spring 18. A friction disk 22 which turns on axis 24 has a knurled lower surface which contacts the surface to be cut. As the knife moves in direction A, disk 22 turns in direction B pulling the slide 12 and blade 16 out to the position seen in FIG. 2 by winding pull wire 28 around cylindrical extension 38 on the side of disk 22 until the flat 26 on disk 22 is exposed to the surface of the work piece being cut. There is another embodiment in FIGS. 4-9 which use gear teeth in place of the pull wire 28.
U.S. Pat. No. 4,936,014 Shannan et al "Utility Knife" a blade B is carried in a carriage 64 as described at Col. 4, lines 15-Col. 5, line 22 which can be retracted and extended.
U.S. Pat. No. 5,490,331 Gold "Utility Knife for Cutting and Scraping" shows a double purpose push-pull knife with a double-edged blade 16. There is a pull-edge 32 for scoring a workpiece. The knife which has a finger contacting member 28 with a surface 30 against which a finger is pressed when the push-blade 26 is being used for scraping. While there is a push-pull feature for extending and retracting the blade in the housing there is no description of that feature.
U.S. Pat. No. 5,025,558 Gilbert "Utility Knives" describes retractable blade features and the housing for the blade.
U.S. Pat. No. 5,042,154 Gilbert "Utility Knives" is closely related to the Gilbert U.S. Pat. No. 5,025,558.
U.S. Pat. No. 5,144,749 Chen "Utility Knife" shows a retractable rotary blade which includes a blade shield. The blade can be pushed or pulled, like a pizza cutting blade.
U.S. Pat. No. 5,301,428 Wilcox "Utility Knife" describes a complicated mechanism which relates to retractability of a blade.
U.S. Pat. No. 5,511,261 Collins "Utility Tool" shows a set of tools which are retractable. Knife blade 54 can be held in a locked position by tightening a screw 28 by turning knob 30 (Col. 4, lines 13-37). There can be alternatives outlined at Col. 3, lines 56-65. The blade does extend down from flat face 39, but face 39 and the blade are not adapted for using the face 39 as a support resting on a workpiece when cutting that workpiece.